I. Field of the Invention
This invention is a rapid and simple method for the differential diagnosis of allergies, sinusitis and upper respiratory tract infections. The method involves the use of either commercially available or novel, specifically adapted, indicator or reagent test strips which are contacted with nasal secretions. Based on the differential read-out from the indicator strip, and a measure of eosinophil infiltration in the nasal secretion a user of the strip is able to determine, with the assistance of a scoring method disclosed herein, whether an allergic condition or an infection is the cause of the respiratory discomfort.
II. Background
It is common for patients afflicted with respiratory discomfort to seek the advice of a clinician in an effort to minimize or overcome their discomfort. Such discomfort generally is attributable to one of the following etiologies: allergic reactions, viral upper respiratory tract infections (URIs), or bacterial infections which can produce sinusitis. However, the clinician presented with such a patient typically has the daunting task of determining which of these three principal etiologies is responsible for the discomfort experienced by a particular patient. The danger inherent in a mis-diagnosis can be quite severe. For example, should the clinician incorrectly diagnose an allergy as sinusitis, a course of antibiotics would typically be prescribed. Naturally, such treatment would do little to alleviate the allergic discomfort being experienced by the patient while at the same time, the patient is exposed to an antibiotic to which there is a possibility of raising a resistant bacterial infection. Should this occur, a problem much more severe than the original allergic condition will have been unwittingly engendered. The prevalence of antibiotic-resistant strains on a global scale due to the over-prescription of antibiotics has become an increasingly recognized problem (Service, R. F., 1995).
In the foregoing example, the availability of a rapid and simple differential diagnostic method would, instead of resulting in a compounded problem, result in the simple recommendation by the clinician that the patient adhere to a course of anti-histamine treatment, allergen avoidance, and/or a regimen of toleragenic desensitization. Unfortunately, however, to date, there is no such simple procedure which will provide the clinician with the necessary differential diagnosis. The accepted method of diagnosis for bacterial sinusitis is expensive radiologic imaging (typically X-ray or CT-scan) of the patients sinuses (see Katz et al., 1995).
Many scientific articles have appeared addressing one or another of the various etiologies of respiratory discomfort. However, no rapid, inexpensive differential diagnostic method has been found. Thus, for example, Wang et al., Correlations between Complaints, Inflammatory Cells and Mediator Concentrations in Nasal Secretions after Nasal Allergen Challenge and during Natural Allergen Exposure, Int. Arch. Allergy Immunology 1995; 106:278-285, disclosed a method of using a nasal microsuction technique. They showed that nasal allergen challenge (NAC) of asymptomatic (out of season) seasonal allergic rhinitis patients results in immediate (5 minutes) increases in histamine, leukotriene C4 (LTC4), and tryptase, with a more gradual (one hour post NAC) and prolonged increase in eosinophil and eosinophil cationic protein (ECP) concentration in nasal secretions. By contrast, in symptomatic (in season allergic rhinitis) patients, high concentrations of eosinophils, ECP, LTC4 and histamine, but not tryptase, were observed. It was concluded that allergic rhinitis is a chronic inflammation of the nasal mucosa, and that infiltration of eosinophils and release of late-phase inflammatory mediators are the predominant pathophysiologic markers. However, this publication neither teaches nor suggests that these observations can be applied to distinguish patients suffering from an allergic condition as opposed to an infection. In addition, the methods used by these authors are laborious and time-consuming and do not involve the use of reagent test strips. Sigurs et al., Eosinophil cationic protein in nasal secretion and in serum and myeloperoxidase in serum in respiratory syncytial virus bronchiolitis: relation to asthma and atopy, Acta Paediatr 1994; 83:1151-5, concluded that it is not possible to predict, from eosinophil cationic protein/albumin ratios in nasal secretions or from ECP and myeloperoxidase concentrations in serum, whether children with respiratory syncytial virus (RSV) bronchiolitis would develop asthma. The publication provides no teaching or suggestion of a method which can easily distinguish patients suffering from an allergic condition as opposed to an infection. The methods used by these authors are laborious and time-consuming and do not involve the use of reagent test strips. Okuda et al., A Novel Method of Counting Eosinophils in Nasal Secretion of Allergic Rhinitis by Hemocytometric Method, Int. Arch. Allergy Immunol. 1994; 104 (suppl. 1):6, disclosed a rapid method for quantitating the number of eosinophils in nasal secretions as a method for diagnosis of allergic rhinitis. The method involves preparation of a solubilized sample of nasal secretion and counting of whole eosinophils. There is no mention of reagent test strips and there is no mention of a method for distinguishing patients suffering from an allergic condition as opposed to an infection.
Kowalski et al., Neutrophil chemotactic activity (NCA) in nasal secretions from atopic and nonatopic subjects, Allergy 1993; 48:409-414, reported that basal nasal secretions of both healthy persons and patients with chronic rhinitis contain significant chemotactic activity to neutrophils. The study also reports that there is an increase in protein content of nasal secretions in patients with perennial allergic rhinitis (AR) following challenge with an antigen. There is no mention of reagent test strips and there is no mention of a method for distinguishing patients suffering from an allergic condition as opposed to an infection.
Igarashi et al., Analysis of nasal secretions during experimental rhinovirus upper respiratory infections, J. Allergy Clin. Immunol. 1993; 92:722-731, studied patients with allergic rhinitis or control subjects inoculated with rhinovirus. Nasal lavage samples pre- and post-infection were analyzed for protein and mast cell mediators. It was found that total protein (including the plasma proteins albumin and IgG and the glandular proteins lactoferrin, lysozyme and secretory IgA) increased post-infection, predominantly due to increased vascular permeability. It was also found that the allergic subjects had fewer symptoms, but greater vascular permeability and greater histamine secretion than control subjects post-rhinovirus infection. Protein was determined by the bicinchoninic acid protein assay (Pierce Chemical Co.) on aliquots of nasal lavage. It is noted at several points in the publication that the symptoms of rhinovirus infected patients and patients with nasal allergic reactions are similar, thus teaching away from the possibility that a simple nasal secretion assay method could be used to distinguish these conditions. Inasmuch as this study is directed at determining the differences in nasal secretions between rhinovirus infected normal or allergic individuals, the study addresses a different problem than that addressed by the instant invention, which is a method for measuring the differences in nasal secretions of patients infected with a rhinovirus, for example, and a patient not infected with a rhinovirus but suffering from allergic rhinitis. The methods used by these authors are laborious and time-consuming and do not involve the use of reagent test strips.
Sperber et al., In vivo detection of a novel macrophage-derived protein involved in the regulation of nasal mucus-like glycoconjugate secretion, J. Allergy Clin. Immunol. 1993; 92:581-588, disclosed a study directed at characterization of a novel 68 Kd nasal mucus secretagogue (NMS-68) released by monocyntes. Inasmuch as this protein was found to be present in nasal tissue of patients with allergic and non-allergic rhinitis, it does not appear to provide a method for distinguishing between these conditions (although the baseline level of this protein is more elevated in the allergic patients). Reagent test strips were not used in this study.
Knani et al., Indirect evidence of nasal inflammation assessed by titration of inflammatory mediators and enumeration of cells in nasal secretions of patients with chronic rhinitis, J. Allergy Clin. Immunol 1992, 90:880-889, examined the nasal lavage cells and six inflammatory mediators released in nasal secretions of four groups of patients with perennial rhinitis and a control group. It was found that patients with symptomatic allergic rhinitis had increased levels of eosinophils, as well as of eosinophil protein X (EPX), LTC4/D4, tryptase, MPO and PGD2. Patients with non-allergic rhinitis were found to have increased neutrophil, tryptase, MPO and EPX concentrations. These measurements provided indirect evidence of nasal inflammation. However, there was no analysis of differences between the nasal secretions of rhinitis patients and patients suffering, for example, from a rhinoviral infection or a bacterial sinus infection.
Klementsson et al., Eosinophils, secretory responsiveness and glucocorticoid-induced effects on the nasal mucosa during a weak pollen season, Clinical and Experimental Allergy 1991; 21:705-710, analyzed the eosinophil influx, the concentration of ECP and secretory responsiveness following methacholine challenge in nasal lavage samples of patients with allergic rhinitis. There was no concurrent analysis of nasal secretions from patients with bacterial sinus or viral infections, and reagent test strips were not employed.
Gordon et al., The pathophysiology of rhinitis, J. Allergy Clin. Immunol. 1991; 88:33-42, challenged patients with seasonal rhinitis on one side of the nose with an allergen and nasal secretions from both sides of the nose were analyzed for protein and mediators. There was no concurrent analysis of nasal secretions from patients with bacterial or viral infections, and reagent test strips were not employed.
Cohen, R. A, and Brestel, E. P., Nasal secretory response to allergen provocation, 1988; 18:435-443, analyzed nasal lavage samples from ragweed-sensitive and control subjects following ragweed pollen challenge. The study revealed no increase in total protein, albumin, potassium, lysozyme activity or peroxidase activity in the control subjects. There were increases in all of these constituents in the ragweed-sensitive subjects. These constituents were assayed by dye binding (Bradford), rocket immunoelectrophoresis, absorption spectroscopy, ABTS (Sigma Chemical Co.) oxidation, and radial diffusion, respectively. Use of reagent test strips is neither taught nor suggested, nor is there a concomitant analysis of these constituents in bacterially or viral infected, no-allergic subjects.
Liu et al., Injurious effect of eosinophil extract on the human nasal mucosa, Rhinology, 1988; 26:121-132, attempted to elucidate the role of eosinophils in nasal secretions of allergic subjects. These authors conclude that the eosinophil extracts tested may actually be harmful to the function of human nasal mucosa. Use of reagent test strips is neither taught nor suggested, nor is there a concomitant analysis of these constituents in infected subjects.
Anderson et al., Allergen-induced nasal hyperactivity appears unrelated to the size of the nasal and dermal immediate allergic reaction, Allergy 1987, 42:631-637, analyzed “priming”, in which nasal lavage samples from hay fever patients were tested following an initial and a re-challenge with allergen. The biochemical parameter used as the measure of the allergic reaction was TAME-esterase via a radiochemical method (release of tritium labeled methanol from the synthetic substrate H3-TAME). Use of reagent test strips is neither taught nor suggested, nor is there a concomitant analysis of these constituents in infected subjects.
Settipane, G. A. and Klein D. E., Non Allergic Rhinitis: Demography of Eosinophils in Nasal Smear, Blood Total Eosinophil Counts and IgE Levels, NER Allergy Proc. 1985; 6:363-366, in an attempt to develop a methodology for differential diagnosis of patients with non-allergic rhinitis, evaluated patients with rhinitis and negative skin tests, (taken to mean that their rhinitis had a non-allergic etiology), for cause of the rhinitis. Nasal smears from these patients were obtained by rolling a swab with nasal secretions on a glass slide, fixing with methanol, staining with Camaco stain (Wright-Giemsa stain), and counting the number of eosinophils per 100 cells. Sinus X-rays were conducted to detect sinusitis. NARES, non-allergic rhinitis with eosinophilia syndrome, is clinically defined in the paper as “nasal congestion/rhinorrhea with negative allergy skin tests, normal serum IgE, and ≧5% eosinophils in the nasal smear.” The purpose of the study was “to attempt to corroborate NARES as a new syndrome and to attempt to further classify and clarify non allergic rhinitis.” There was no discussion in this paper regarding the problem of misidentification of this clinical condition with upper respiratory tract infections, and use of reagent test strips as part of the differential diagnosis is neither disclosed nor suggested.
Brofeldt, et al., Biochemical Analysis of Nasal Secretions induced by Methacholine, Histamine, and Allergen Provocations, Am. Rev. Respir. Dis. 1986; 133:1138-1142, obtained methacholine, histamine and allergen induced nasal secretions from subjects over a fifteen minute post-induction period. The nasal secretions were weighed and tested for hexose content (orcinol method), protein content (Lowry method), carbohydrate (gas liquid chromatography), sialic acid (colorimetric thiobarbituric acid assay), inorganic sulphate (radioactive BaCl2), DNA (diphenylamine), albumin and immunoglobulins (rocket immunoelectrophoresis or ELISA). The different inducers were found to have differential effects on the various elements tested. However, there was no concomitant study of nasal secretions from patients suffering from an infection nor was the use of reagent test strips taught or suggested.
Eggelston, et al., Mediators Of Immediate Hypersensitivity in Nasal Secretions during Natural Colds and Rhinovirus Infection Acta Otolaryngol. 1984; suppl. 413:25-35, note that “[v]iral respiratory infections and allergic rhinitis have many similarities. Not only are symptoms similar in the two conditions, but the pathologic anatomy of both is dominated by vascular dilatation and edema with minimal cellular infiltrate in acute phases . . . ” The authors postulated that these similarities are due to mast cell activation during infection, resulting in release of histamine. However, they report that spectrofluorometric analysis of histamine in nasal secretions of control subjects or patients with a natural cold or with a rhinovirus infection does not support this hypothesis. Histamine concentrations were found to be generally lower in individuals infected with influenza A or rhinovirus. TAME-esterase was also found not to be elevated during these infections. This article reports that during viral respiratory tract infection there is little or no esterase elevation, while in allergic rhinitis there is esterase elevation (see discussion at page 34 of the reference). However, the use of reagent test strips for this purpose is neither taught nor suggested, nor is there a discussion of how these results could be used in a differential diagnostic method also aimed at distinguishing sinusitis.
Baumgarten, et al., Plasma Kallikrein During Experimentally Induced Allergic Rhinitis: Role in Kinin Formation and Contribution to TAME-Esterase Activity in Nasal Secretions, J. Immunol. 1986; 137:977-982, report the observation that when allergic and non-allergic individuals are challenged intranasally with an allergen, post-challenge nasal lavages of only the allergic individuals contained elevated levels of immunoreactive human plasma kallikrein/prekallikrein (iHPK). This increase in iHPK correlated with increases in kinins, histamine, TAME-esterase, and clinical symptoms. In fact, these researchers argue that the TAME-esterase activity is produced by plasma kallikrein and mast cell tryptase. Thus, iHPK may be an additional marker that could be used in a reagent test strip for allergic rhinitis diagnosis. However, in this study, esterase was assayed by a radiochemical method and kinins were assayed using a radioimmunoassay, rather than by any type of reagent test strip.
Anderson et al., Mechanisms of nasal hyper-reactivity, Eur. Arch. Otorhinolaryngol. 1995; 252 (suppl. 1):S22-S26, review the factors known to be involved in allergen-induced nasal hyper-reactivity. However, there is no teaching or suggestion of a method for distinguishing allergic from infection related rhinitis. Reagent test strips for this purpose are neither proposed nor suggested.
Florman, et al., Rapid Non-invasive Techniques for Determining Etiology of Bronchitis and Pneumonia in Infants and Children, Clin. Chest Med. 1987; 8:669-679, provide a review of techniques for differential diagnosis of the causative agent in lower respiratory tract infections. A number of rapid, non-specific and specific tests are mentioned. However, there is no mention of differential diagnosis of allergic from infective conditions and reagent test strips for this purpose are neither disclosed nor suggested.
Katz et al., A comparison of Imaging Techniques in Patients with Chronic Sinusitis (X-Ray, MRI, A-Mode Ultrasound) Allergy, Proc. 1995; 16:123-127, demonstrate the long-felt need for a rapid, inexpensive way to diagnose sinusitis and distinguish this condition from allergic rhinitis. The method of the instant invention has the potential for supplanting the much more expensive diagnostic techniques reported in this paper to be most reliable in diagnosis of sinusitis (CAT scans and MRI).
Demoly et al., Assessment of Inflammation in noninfectious chronic maxillary sinusitis, J. Allergy Clin. Immunol. 1994; 94:95-108, suggest that it might be possible to distinguish sinusitis (infection) from allergic rhinitis based on the contents of nasal mucosa. However, the techniques used in attempting to distinguish these conditions depended on the use of immunohistochemistry of surgical specimens, immunocytochemistry of lavage fluids, and measurement of specific inflammatory mediators in sinus lavage fluids (ELISA, RIA). There is no teaching or suggestion that reagent dip-sticks could be used for this purpose.
Accordingly, there has been a long-felt need in the art for a rapid, inexpensive, non-invasive technique for a method capable of distinguishing between allergies and infections. The method of the instant invention involves testing nasal secretions with commercially available (Ames Division, Miles Laboratories, Inc. Elkhart, Ind. 46515) or novel or modified reagent test strips. The commercially available strips, also referred to as dipsticks, test for pH, protein, glucose, ketone, white blood cell esterase, bilirubin and blood.
The following U.S. patents which may be relevant to the instant invention are listed on the product insert of the Miles Laboratories Inc., reagent test strips, and are herein incorporated by reference:    1) U.S. Pat. No. 3,438,737—Protein test composition and method of detecting proteins in fluids using the test composition.    2) U.S. Pat. No. 4,301,115—Test device having resistance to cross contamination between reactant areas and process for making it.    3) U.S. Pat. No. 4,637,979—Composition and test device for determining the presence of leukocytes containing a zwitterion coupling agent for determining the presence of leukocytes, esterase or protease in a sample.    4) U.S. Pat. No. 4,645,842—Pyrrole composition for detecting presence of hydrolytic analytes, useful in the detection of leukocytes, esterase and protease in a test sample.    5) U.S. Pat. No. 4,657,855—Composition and test device for determining the presence of leukocytes, esterase and protease in a test sample.    6) U.S. Pat. No. 4,704,460—Novel compounds for detecting the presence of hydrolytic analytes in a test sample which indicates the presence of leukocytes, esterase and protease in a test sample.    7) U.S. Pat. No. 4,758,508—Analytical process and agents for the detection of esterolytic and/or proteolytic enzymes in a liquid sample.
The following U.S. patents which may be relevant to the instant invention are listed on the product insert or packaging of Boehringer Mannheim Corporation's reagent test strips, and are herein incorporated by reference:    1) U.S. Pat. No. 3,359,072—A protein determination method.    2) U.S. Pat. No. 3,418,079—A protein determination device and method.    3) U.S. Pat. No. 3,712,853—A nitrite detection reagent and method.    4) U.S. Pat. No. 3,897,214—A diagnostic device.    5) U.S. Pat. No. 3,802,842—A reagent test strip.    6) U.S. Pat. No. 4,013,416—A protein detection method.    7) U.S. Pat. No. 4,385,114—An oxidation indicator system.
However, none of these patents disclose or suggest a method for testing nasal mucous secretions to distinguish allergic from infectious conditions.
In the method of this invention, a sample of a patient's nasal secretions is tested and, based on the pH, amount of protein, nitrite and leukocyte esterase and eosinophils, it can quickly be determined if the patient is suffering from an allergy, a simple viral infection, or bacterial sinusitis. The method has the potential to supplant much more expensive and invasive clinical procedures.